nonenzymatic proteins Flashcards
proteome
range of proteins expressed in an organism
cytoskeleton
cell division, structure, and organelle transport support
- made of microfilaments, microtubules, and intermediate filaments
what polymers constitute a significant part of the cytoskeleton
actin and tubulin
arrange the protein filaments of the cytoskeleton from smallest to largest
microfilaments, intermediate filaments, microtubules
function of actin microfilaments
motility and structure
- interact with myosin during muscle contraction
- contribute to cytokinesis during cell division
G-actin
individual monomers of actin
F-actin
polymer of g actin that forms microfilaments
how many strands of f actin make microfilament
2
T/F actin polymerization is energetically costly
True, ATP is added to the + chain of the growing polymer
the - end shrinks
tredmilling
actin simultaneously grows at the + end while shrinking at the - end , rapid growth and assembly for dynamic cytoskeleton
structure of intermediate filaments
long alpha helical structures that resemble cork screws
- rigid and resist force
- can be stretched far beyond length
function of intermediate filaments
cell adhesion and structrual support
what is keratin
intermediate filament that makes up hair and nails
microtubule structure
hollow cylinders composed of dimers of alpha tubulin and beta tubulin
function of microtubules
- movement in chromosomes during M phase
- formation of cillia and flagella
- intracellular transport
what are cilia and flagella composed of
microtubules
where is microtubule formation initiated
in the Microtubule Organizing Centers (MTOCs) of centrosome and basal bodies of cilia and flagella
what are the building blocks of microtubules
alpha and beta tubulin dimers which polymerize using GTP
critical concentration
specific amount of dimers of a and b tubulin necessary to initiate tubule polymerization
motor proteins
kinesins, dyneins, and myosins
kinesins
use energy from ATP to move along microtubules and transport cargo
- anterograde transport (move membrane components that are bound for the membrane to periphery of cell)
structure of kinesin
heterotetramer of 2 heavy chains and 2 light chains attached to a microtubule that walks cargo
dyneins
motor proteins that carry cargo along microtubules through retrograde transport
axonemal dyneins
found only in cells with flagella and cilia
- generate sliding motion
cytoplasmic dyneins
transport cargo needed to carry out cellular functions within cytoplasm
myosins
ATPases that are important to muscle contraction
- contain head, neck, and tail regions
myosin head
binds to actin and hydrolyzes atp to generate force for contraction
power stroke
force created by myosin that allows the energy to be released via atp hydrolysis and actin and myosin bind tightly
atp triggers what in muscle contraction
myosin release from actin
cell adhesion
Cell adhesion molecules (CAMs) associated with cytoskeleton and play a role in the ECM
classes of CAMs
selectins, cadherins, integrins
selectins
family of CAMs that mediate inflammatory response
in immune cells platelets and endothelial lining of blood vessels
cadherins
calcium dependend CAMs that are involved in early growth and development which bind to microfilaments of cytoplasm
- transmembrane proteins
- bulk of cadherin is outside fo the cell
adherins
clumps of cadherins that bind cells of a tissue together
integrins
transmembrane proteins that act as adhesion and signaling molecules
types of cell junctions
anchoring, gap , and tight
anchoring junction
adheren junctions
- connect cytoskeleton of one cell with other cells and contribute to stability of tissue
- can be with cadherins or ECM
desmosomes
involve cadherins connected to intermiediate filaments to other cells
hemidesmosomes
integrins connect to the intermediate filaments of the ECM
gap juncitons
connexin proteins
- enable communication
common locatoin of gap junctions
cardiomyocytes
tight junctions
found in epithelial cells
prevent communicaiton between cells
BBB
leaky epithelia
relatively few tight junctions in an epitheial tissue
- kidney
antibodies
glycoproteins producted by b cells of the adaptive immune system
- bind to antigens
antigens
particles recognized as foreign by the body that bind to antibodies
B cell receptor
antibody bound to the membrane of a B cell
structure of an antibody
basic y shape with two heavy chains (bottom) and two light chains (top)
- heavy chains are constant region
- light chains contain varibl e region
contant region
heavy chains of antibody that are uniform among different antibodies
IgA antibodies
mucosal areas to help prevent colonization of pathogens
IgD antibodies
act as antigen receptor on B cells that have not been exposed to antigens
- activates mast cells and basophils
IgE antibodies
involved in allergies and antiparasitic response
- IgE binds to allergen causing histimine release
IgG
most of humoral response , can cross placenta and confer passive immunity to fetus
IgM
mounts an immune response and eliminates pathogens in early stages of humoral response
- before IgG levels increase
intacrine signalling
produced by the target cell and stay within the target cell
autocrine cells
produced and effected by the same cell via its own receptors
juxtacrine signals
target cells in contact with signal
paracrine signals
target cells in general vicinity
endocrine signals
travel through ciruculatory system
types of membrane receptors
ion channels, enzyme linked, GPCR
GPCR
when receptor binds to ligand, there is a confirmational change in gtp to activate and turn on adenylate cyclase which makes cAMP to phosphorylate other proteins
gtp hydrolysis
inactivation of g protein , is done by gtpases
what does cAMP turn on
protein kinase A
strcutures of a nuclear receptor
ligand binding domain and the dna binding domain
active g protein
alpha subunit bound to gtp
inactive g protein
a, b, gamma bound to gdp
